A cooling device

ABSTRACT

There is disclosed a cooling system. The cooling system comprises a main cooling unit and a main chilling unit in fluid communication with a heat exchanger, the main chilling unit being configured to cool a liquid coolant for use with the heat exchanger. The cooling system further comprises a back-up cooling unit that includes a cooling reservoir including a plurality of small-sized self-contained cooling accumulators; a secondary chilling unit configured to cool the plurality of small-sized cooling accumulators, during a charging phase; a valve configured to selectively couple the cooling reservoir to the main cooling unit during a release phase so that the plurality of small-sized cooling accumulators provide a heat sink to cool the cooling fluid for the main cooling unit.

CROSS-REFERENCE

The present application claims convention priority to Russian UtilityModel Application No. 2013140369, filed on Aug. 30, 2013, entitled

. This application is incorporated by reference herein in its entirety.

FIELD

The present technology relates to cooling devices in general andspecifically to a cooling device for a dwelling or equipment.

BACKGROUND

There are many industries where cooling may be desirous or required.Some of these industries require precise control of cooling. Othersrequire cooling that is un-interrupted and does not stop in case ofpower failure, for example. Some of these industries include but are notlimited to: telecommunications, medical industry, precise manufacturingand the like. Same problems exist for companies who maintain computerequipment (such as servers or the like). As the number of equipmentco-located in a given dwelling grows, the equipment heats up fast andrequires continuous cooling for un-interrupted operations.

It is known in the art to use stationary or mobile air-conditioningunits that allow for precise temperature control. Naturally, all of thisequipment requires power supply in order to operate. There have beensome attempts in the art to address the problems associated with back-uppower and/or alternative cooling sources, especially for thoseindustries where continuous cooling is a critical parameter foroperational stability. For companies who operate computer equipmentand/or servers, the uninterrupted cooling of computer equipment and/orservers can be a critical operational parameter to ensure uninterrupteddata processing and integrity of the computing equipment and/or servers.

US patent application US2007/0132317 discloses, for example, powersystem that serves as a source of dedicated back-up power for a coolingsystem. The power system utilizes a plurality of fuel cells, whichproduce direct current (DC) power. A conversion device, such as aninverter, is used to convert the DC into alternating current (AC) forpowering the cooling system. A transfer switch connects the AC powerfrom the inverter to the cooling system. The position of the transferswitch determines the source of AC power for the cooling system.

US patent application 2010/0170663 teaches a backup cooling storagesystem, which comprises at least one cooling and storage unit configuredto cool a liquid supply using a quantity of cooled material when a mainchiller of the liquid supply is not operational, and at least onechilling element configured to generate the quantity of cooled materialfor the at least one cooling and storage unit when the main chiller ofthe liquid supply is operational. Additional embodiments and methods arefurther disclosed.

SUMMARY

It is an object of the present technology to ameliorate at least some ofthe inconveniences present in the prior art.

In one aspect, implementations of the present technology provide acooling system. The cooling system comprises a main cooling unit and amain chilling unit in fluid communication with a heat exchanger, themain chilling unit being configured to cool a liquid coolant for usewith the heat exchanger. The cooling system further comprises a back-upcooling unit that includes a cooling reservoir including a plurality ofsmall-sized self-contained cooling accumulators; a secondary chillingunit configured to cool the plurality of small-sized coolingaccumulators, during a charging phase; a valve configured to selectivelycouple the cooling reservoir to the main cooling unit during a releasephase so that the plurality of small-sized cooling accumulators providea heat sink to cool the cooling fluid for the main cooling unit.

In another aspect, implementations of the present technology provide aback-up cooling unit for the use with a main cooling unit. The back-upcooling unit comprises a cooling reservoir including a plurality ofsmall-sized self-contained cooling accumulators; a secondary chillingunit configured to cool the plurality of small-sized coolingaccumulators, during a charging phase; a valve configured to selectivelycouple the cooling reservoir to the main cooling unit during a releasephase so that the plurality of small-sized cooling accumulators providea heat sink to cool the cooling fluid for the main cooling unit.

Additional and/or alternative features, aspects and advantages ofimplementations of the present technology will become apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present technology, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings, where:

FIG. 1 depicts a schematic diagram of a cooling system 100, the coolingsystem 100 being implemented in accordance with non-limiting embodimentsof the present technology.

FIG. 2 depicts a schematic diagram of a back-up cooling unit 216, theback-up cooling unit 216 being implemented in accordance with anothernon-limiting embodiment of the present technology.

DETAILED DESCRIPTION

With reference to FIG. 1, there is depicted a cooling system 100, thecooling system 100 being implemented in accordance with non-limitingembodiments of the present technology. It should be noted that where thecooling system 100 can be used is not at all limited. For example, thecooling system 100 can be used by a service provider (not depicted), theservice provider operating a number of servers or other computingdevices. Within those embodiments, the cooling system 100 may be used tocool a room (or multiple rooms) where the servers or other computingdevices are located. In other embodiments of the present technology, thecooling system may be used by a hospital to cool patient rooms orroom(s) storing equipment and/other computing devices.

In the above examples, it is possible to say that the cooling system 100is implemented as a stationary cooling system, in a sense that it is notmovable and is more or less located in a single geographical location.It is also possible to implement the cooling system 100 as a mobilecooling station, for example, the cooling system 100 can be used to coolgoods in transit. There are numerous examples of goods that need to betransported from one geographical location to another geographicallocation, while requiring constant cooling—such as perishable food itemsor medical goods (such as for example, transplant organs).

The cooling system 100 comprises a main cooling unit 102. In someembodiments of the present technology, the main cooling unit 102 can beimplemented as a conventional air conditioning unit and the like. Themain cooling unit 102 comprises a main chilling unit 104. The mainchilling unit 104 is configured to chill a cooling fluid, which coolingfluid is used within the main cooling unit 102. In some embodiments ofthe present technology, the cooling fluid used in the main cooling unit102 is implemented as Chlorofluorocarbon (CFC) refrigerant,Hydrochlorofluorocarbon (HCFC) refrigerant, or Hydrofluorocarbon (HFC)refrigerant, also known as FREON—a trade-mark of DuPont withheadquarters in Wilmington, Del., United States of America

The main chilling unit 104 is in fluid communication with a heatexchanger 106 via a cooling fluid line 108. The main chilling unit 104is configured to chill a cooling fluid, to supply the chilled coolingfluid to the heat exchanger 106 and to receive the warmed up coolingfluid from the heat exchanger 106 (the warmed up cooling fluid havingbeen warmed up with by contact with a heat exchanger or another type ofa heat source).

There is also provided a pump 110. The pump 110 is configured to propelthe cooling fluid through the cooling fluid line 108. Both the mainchilling unit 104 and the pump 110 are coupled (directly or indirectly)to a source of power 112, which can be a standard power grid connection.It should be noted that the main cooling unit 102 (i.e. the mainchilling unit 104, the heat exchanger 106 and the pump 110) can beimplemented as substantially known in the art.

There is also provided a back-up source of power 180, the back-up sourceof power 180 being implemented as substantially known in the art. Forexample, the back-up source of power 180 of the type described in the USpatent application US 2007/0132317 can be used. Within embodiments ofthe present technology, the pump 110 is also connected to the back-upsource of power 180. In some embodiments, the main cooling unit 102 canbe also additionally coupled to the back-up source of power 180.

In accordance with non-limiting embodiments of the present technology,the cooling system 100 further comprises a back-up cooling unit 116. Theback-up cooling unit 116 comprises a cooling reservoir 118. The coolingreservoir 118 is configured to house, in use, a plurality of small-sizedself-contained cooling accumulators 120.

In one non-limiting embodiment of the present technology, the pluralityof small-sized self-contained cooling accumulators 120 is implemented ascontainers housing a phase-change material. An example of suchcontainers is provided by Cryogel of San Diego, Calif., United States ofAmerica. Another example of such containers is provided by Phase ChangeMaterial Products Limited of Yaxley, Cambridgeshire, United Kingdom ofGreat Britain and Northern Ireland.

Now, it should be expressly understood that the shape or the exact sizeof each one within the plurality of small-sized self-contained coolingaccumulators 120 is not particularly limited. For example, in someembodiments of the present technology, each of the plurality ofsmall-sized self-contained cooling accumulators 120 is implemented asball-shaped container (as depicted in FIG. 1). Within these specificnon-limiting embodiments, each of the plurality of small-sizedself-contained cooling accumulators 120 can be implemented as a ballhaving a diameter of approximately 10 cm. The plurality of small-sizedself-contained cooling accumulators 120 can, as an example, be filledwith fluid, the fluid being a mixture of a salt and water.

In other non-limiting embodiments of the present technology, each of theplurality of small-sized self-contained cooling accumulators 120 isimplemented as longitudinal sticks or square-like boxes. It should benoted that not all of the plurality of the small-sized self-containedcooling accumulators 120 need to implemented identical to each other. Inother words, some of the small-sized self-contained cooling accumulators120 may be implemented in a different form factor from other ones of theplurality of the small-sized self-contained cooling accumulators 120.

In some embodiments of the present technology, the plurality ofsmall-sized self-contained cooling accumulators 120 is filled with asolution of a salt (or salts) and water. The solution can be selectedsuch that to have a phase change temperature below zero degrees Celsius.In other embodiments, the plurality of small-sized self-containedcooling accumulators 120 can be filled with salt hydrates, which canhave the change phase temperature of above zero degrees Celsius.

Finally, the plurality of small-sized self-contained coolingaccumulators 120 can house organic materials, such as polymers with longchain molecules composed primarily of carbon and hydrogen. Thesematerials tend to exhibit high orders of crystallinity when freezing andmostly change phase above zero degrees Celsius. Examples of organicmaterials used as phase change materials include (but are not limitedto) waxes, oils, fatty acids and polyglycol s.

It should be expressly noted that the shape and the size, as well as thematerial used within, the plurality of small-sized self-containedcooling accumulators 120 can be selected by the operator of the coolingsystem 100 based on the specific cooling needs, the size of the dwellingto be cooled, the back-up cooling time required and the like.

Within the back-up cooling unit 116, there is also provided a secondarychilling unit 122. The secondary chilling unit 122 can be implementedsimilarly to the main chilling unit 104. To that extent, the secondarychilling unit 122 can also be coupled to the source of power 112. In analternative non-limiting embodiment of the present technology, thesecondary chilling unit 122 can be also coupled to the back-up source ofpower 180 in addition to the source of power 112.

In some embodiments of the present technology, the secondary chillingunit 122 can also use FREON as the cooling fluid. In alternativeembodiments, the secondary chilling unit 122 can use CO₂. In someembodiments of the present technology, the use of CO₂ as the coolingfluid can make implementations of the secondary chilling unit 122 moreenvironmentally friendly.

In yet additional non-limiting embodiments of the present technology,the secondary chilling unit 122 can be implemented as the main chillingunit 104. In other words, within those non-limiting alternativeembodiments, the main chilling unit 104 can also serve the purpose ofthe secondary chilling unit 122. In those embodiments, description ofoperation of the secondary chilling unit 122 can apply mutatis mutandisto the embodiments where the main chilling unit 104 is used in lieu ofthe secondary chilling unit 122.

The back-up cooling unit 116 further includes a first valve 124. Thefirst valve 124 can be implemented as a standard switch valve.Alternatively, the first valve 124 can be implemented as a proportionalvalve. In some embodiments of the present technology, the first valve124 is coupled to the source of power 112. In alternative non-limitingembodiments, additionally the valve 124 can be also coupled to theback-up source of power 180. Alternatively, the first valve 124 can beunder a control of a control entity (not depicted), the control entitybeing coupled to the source of power 112 and/or the back-up source ofpower 180. The first valve 124 can comprise three ports: a first valveport 124 a, a second valve port 124 b and a third valve port 124 c.

The back-up cooling unit 116 further includes a second valve 126. Thesecond valve 126 can be implemented as standard switch valve.Alternatively, the second valve 126 can be implemented as a proportionalvalve. In some embodiments of the present technology, the second valve126 is coupled to the source of power 112. In alternative non-limitingembodiments, additionally the second valve 126 can also be coupled tothe back-up source of power 180. Alternatively, the second valve 126 canbe under a control of the control entity (not depicted), the controlentity being coupled to the source of power 112 and/or the back-upsource of power 180. The second valve 126 can comprise three ports: afirst valve port 126 a, a second valve port 126 b and a third valve port126 c.

The first valve 124 and the second valve 126 can perform switching ofvarious cooling lines. Within the back-up cooling unit 116, there areprovided: (i) a first cooling line 140 fluidly coupling a cooling fluidintake (not separately numbered) of the cooling reservoir 118 and thefirst port 124 a of the first valve 124; (ii) a second cooling like 142fluidly coupling the third port 124 c of the first valve 124 and thecooling line 108; (iii) a third cooling line 144 fluidly coupling acooling fluid outlet of the cooling reservoir 118 and the first port 126a of the second valve 126; (iv) a fourth cooling line 146 fluidlycoupling the third port 126 c of the second valve 126 and the coolingline 108; and (v) a fifth cooling line 148 fluidly coupling the secondport 124 b of the first valve 124 and the second port 126 b of thesecond valve 126.

As such, the first valve 124 and the second valve 126 can selectivelyfluidly couple (i) the first cooling line 140, the fifth cooling line148 and the third cooling line 144 or (ii) the first cooling line 140and the second cooling line 142, as well as the third cooling line 144and the fourth cooling line 146. Within the configuration (i) the firstport 124 a and the second port 124 b of the first valve 124, as well asthe first port 126 a and the second port 126 b of the second valve 126are open, while the third port 124 c of the first valve 124 and thethird port 126 c of the second valve 126 are closed.

Within the configuration (ii) the first port 124 a and the third port124 c of the first valve 124, as well as the first port 126 a and thethird port 126 c of the second valve 126 are open, while the second port124 b of the first valve 124 and the second port 126 b of the secondvalve 126 are closed.

Effectively, in the configuration (i), the cooling line 108 isdisconnected from the back-up cooling unit 116 and in the configuration(ii), the cooling line 108 is connected to the back-up cooling unit 116.

In some embodiments of the present technology, the fluid resistancewithin the second cooling line 142 and the fourth cooling line 146 ishigher than the fluid resistance within the cooling line 108 of the maincooling unit.

Even though not depicted in FIG. 1, the cooling reservoir 118 comprisesinternal piping for directing a flow of cooling fluid around theplurality of small-sized self-contained cooling accumulators 120. Theshape and layout of this internal piping (not depicted) is not limitedand will depend on numerous factors, as will be appreciated by those ofskill in the art.

The back-up cooling unit 116 is configured to execute two modes ofoperations—a charging phase and a release phase. In the charging phase,the first valve 124 and the second valve 126 are actuated to fluidlycouple the first cooling line 140, the fifth cooling line 148 and thethird cooling line 144. Within this configuration, the secondarychilling unit 122 supplies cooling fluid to the cooling reservoir 118,while the cooling reservoir 118 is disconnected from the cooling line108 (or, in other words, is disconnected from the main cooling unit102).

It is noted that in embodiments of the present technology, the coolingfluid so supplied to the cooling reservoir 118 is cooled to or below thetemperature for the substance contained in the plurality of small-sizedself-contained cooling accumulators 120 to freeze (i.e. to shift phase).Hence, it can be said that during the charging phase, the plurality ofsmall-sized self-contained cooling accumulators 120 get “charged” withback-up cooling power. In some embodiments of the present technology,the charging phase can be executed during low-demand time for electricpower. For example, the charging phase can be executed during low-demandtime for electric power, as an example, the charging phase can beimplemented at night.

In the release phase, the first valve 124 and the second valve 126 areactuated to fluidly couple the first cooling line 140 and the secondcooling line 142, as well as the third cooling line 144 and the fourthcooling line 146. In some embodiments of the present technology, therelease phase can be turned on automatically, in case of the powerfailure. This automatic switching can be executed by the aforementionedcontrol entity (not depicted). In alternative embodiments, the releasephase can be turned on by an operator, when needed (for example, duringthe power failure).

Within this configuration, the cooling fluid from the cooling line 108enters the cooling reservoir 118 and gets in contact with plurality ofsmall-sized self-contained cooling accumulators 120. Effectively, theplurality of small-sized self-contained cooling accumulators 120 areused to cool the cooling fluid in the cooling line 108 by acting as aheat sink for the thermal energy within the warmed (or used) coolingfluid.

Within some embodiments of the present technology, within the releasephase the main chilling unit 104 is turned off. In some embodiments, thesecondary chilling unit 122 is also turned off. In some embodiments, themain chilling unit 104 and the secondary chilling unit 122 are turnedoff by virtue of lack of power (for example, in those embodiments whereone or both of them are not coupled to the back-up source of power 180).Recalling that both the main chilling unit 104 and the secondarychilling unit 122 may be coupled to back-up source of power 180, themain chilling unit 104 and the secondary chilling unit 122 can be eitherturned off or disconnected from the back-up source of power 180. As willbe explained momentarily, this is done in the interest of conservingback-up energy.

Within these embodiments, during the release phase, the back-up powercan be used to provide power to the pump 110, the fans (not depicted)within the main cooling unit 102 and a controller (not depicted)responsible for controlling the cooling system 100. Generally speaking,the back-up power can be used to power only those components of thecooling system 100 that are critical for maintaining cooling within thecooling system 100 until the main power is restored (or at least anemergency generator can be turned on). In sense, some embodiments of thepresent technology allow to separate back-up cooling energy (provided bythe plurality of small-sized self-contained cooling accumulators 120)and the back-up power (provided by the back-up source of power 180) andto focus the energy from the back-up source of power 180 on only“cooling-critical” components of the cooling system 100.

A technical effect of embodiments of the present technology allowspreserving a portion of the back-up power and, hence, allows for longeruse of the back-up power. The preservation of the portion of the back-uppower is done, at least partially, by concentrating the use of theback-up power on motivating only those devices within the cooling system100 that are “must have” for propelling of cooling fluid (and, thusmaintaining the cooling) while the main power is down. Alternatively oradditionally, a technical affect of embodiments of the presenttechnology may include ability to use a smaller back-up power source.

In some embodiments of the present technology, the back-up cooling unit116 can be located in a freight container, such as those typically usedfor sea freight. Within those embodiments, the back-up cooling unit 116can be mobile. Alternatively or additionally, the back-up cooling unit116 can be implemented as stackable back-up cooling unit. In otherwords, depending on the needs, one or more of the back-up cooling units116 can be used at in a given site of the cooling system 100.

In other words, the back-up cooling unit 116 can be implemented as amodular system. Within such modular implementations, the stacked ones ofthe back-up cooling unit 116 can be fluidly coupled in parallel or insequence. Additionally or alternatively, depending on the cooling needs,some of the stacked back-up cooling units 116 can be used to cool asubset of the dwellings or equipment to be cooled, while the others ofthe stacked back-up cooling units 116 can be used to cool another subsetof the dwellings or equipment to be cooled.

With reference to FIG. 2, there is depicted an alternative embodiment ofa back-up cooling unit 216. The back-up cooling unit 216 can be executedsubstantially similar to the back-up cooling unit 116 of FIG. 1 and assuch, the description to be presented herein below will focus primarilyon the differences between implementations of FIG. 1 and FIG. 2.

Much akin to the back-up cooling unit 116, the back-up cooling unit 216comprises a cooling reservoir 218. The cooling reservoir 218 isconfigured to house, in use, a plurality of small-sized self-containedcooling accumulators 220. Within the back-up cooling unit 216, there isalso provided a secondary chilling unit 222. The back-up cooling unit216 further includes a first valve 224 and a second valve 226.

Within the embodiments of FIG. 2, the cooling reservoir 218 isimplemented with varying volume. Within these embodiments, there isprovided a compensator 240, the compensator 240 being configured tocompensate for the volume expansion or contraction within the coolingreservoir 218.

In a specific non-limiting implementation of the cooling system 100 orcooling system 200, the following parameters can be used. The power ofthe full energy release during the release phase is Qcol=400 kWh. Theavailable cooling back-up from the secondary cooling unit 116, 216 is0.5 hours. The time required to charge the plurality of small-sizedself-contained cooling accumulators 220 is 12.5 hours. The powerconsumption during the charging phase is N=12 kWh. The cooling power ofthe main cooling unit 102 is q=32 kWh.

It should be expressly understood that the parameters presented aboveare used as an example only. Those skilled in the art, having read andappreciated teachings provided herein, will be able to modify the aboveparameters to suit their cooling and back-up needs. For example, shouldone desire to increase the cooling back-up time, one may increase thesize of the cooling reservoir 118. Alternatively, one may choose tostack several ones of the back-up cooling unit 116.

It should be expressly understood that not all technical effectsmentioned herein need to be enjoyed in each and every embodiment of thepresent technology. For example, embodiments of the present technologymay be implemented without the user enjoying some of these technicaleffects, while other embodiments may be implemented with the userenjoying other technical effects or none at all.

Modifications and improvements to the above-described implementations ofthe present technology may become apparent to those skilled in the art.The foregoing description is intended to be exemplary rather thanlimiting. The scope of the present technology is therefore intended tobe limited solely by the scope of the appended claims.

1. A cooling system comprising: a main cooling unit including a heatexchanger; a main chilling unit in fluid communication with the heatexchanger, the main chilling unit being configured to cool a liquidcoolant for use with the heat exchanger; and a back-up cooling unitincluding: a cooling reservoir including a plurality of small-sizedself-contained cooling accumulators; a secondary chilling unitconfigured to cool the plurality of small-sized cooling accumulators,during a charging phase; a valve configured to selectively couple thecooling reservoir to the main cooling unit during a release phase sothat the plurality of small-sized cooling accumulators provide a heatsink to cool the cooling fluid for the main cooling unit, the coolingreservoir being implemented with varying volume, the cooling reservoirhaving a compensator configured to compensate for the volume expansionand contraction within the cooling reservoir.
 2. The cooling system ofclaim 1, wherein the valve is further configured to de-couple thecooling reservoir from the main cooling unit during said charging phase.3. The cooling system of claim 1, wherein the valve comprises a switchvalve.
 4. (canceled)
 5. The cooling system of claim 1, wherein theplurality of small-sized self-contained cooling accumulators house aphase change material.
 6. (canceled)
 7. The cooling system of claim 5,wherein the cooling fluid used in the secondary cooling unit is chilledto or below the phase change temperature of the phase change material.8. (canceled)
 9. The cooling system of claim 1, wherein the secondarycooling unit uses a cooling fluid and the cooling fluid is implementedas CO₂.
 10. (canceled)
 11. (canceled)
 12. (canceled)
 13. (canceled) 14.The cooling system of claim 1, further comprising a back-up source ofpower.
 15. (canceled)
 16. (canceled)
 17. The cooling system of claim 1,wherein during said release phase, the main chilling unit is turned off.18. The cooling system of claim 1, wherein during said release phase,the secondary chilling unit is turned off.
 19. (canceled)
 20. (canceled)21. The cooling system of claim 1, wherein the secondary chilling unitand the main chilling unit are implemented as the same device.
 22. Amethod of operating unit of claim 1, wherein the charging phase isimplemented during off-peak demand time.
 23. A back-up cooling unit forthe use with a main cooling unit, the back-up cooling unit comprising: acooling reservoir including a plurality of small-sized self-containedcooling accumulators; a secondary chilling unit configured to cool theplurality of small-sized cooling accumulators, during a charging phase;a valve configured to selectively couple the cooling reservoir to themain cooling unit during a release phase so that the plurality ofsmall-sized cooling accumulators provide a heat sink to cool the coolingfluid for the main cooling unit, the cooling reservoir being implementedwith varying volume, the cooling reservoir having a compensatorconfigured to compensate for the volume expansion and contraction withinthe cooling reservoir.
 24. The back-up cooling unit of claim 23, whereinthe valve is further configured to de-couple the cooling reservoir fromthe main cooling unit during said charging phase.
 25. The back-upcooling unit of claim 23, wherein the valve comprises a switch valve.26. The back-up cooling unit of claim 23, wherein the valve comprises afirst valve and a second valve.
 27. The back-up cooling unit of claim23, wherein the plurality of small-sized self-contained coolingaccumulators house a phase change material.
 28. (canceled)
 29. Theback-up cooling unit of claim 27, wherein the cooling fluid used in thesecondary cooling unit is chilled to or below the phase changetemperature of the phase change material.
 30. (canceled)
 31. The back-upcooling unit of claim 23, wherein the secondary cooling unit uses acooling fluid and the cooling fluid is implemented as CO₂. 32.(canceled)
 33. (canceled)
 34. (canceled)
 35. (canceled)
 36. (canceled)37. The back-up cooling unit of claim 23, wherein during said releasephase, the main chilling unit is turned off.
 38. The back-up coolingunit of claim 23, wherein during said release phase, the secondarychilling unit is turned off.
 39. (canceled)
 40. (canceled)